Be My Parabatai
by OmgAdot
Summary: "Whither thou goest, I will go; Where thou diest, will I die And there will I be buried: The Angel do so to me, and more also, if aught but death part thee and me." Those were the words exchanged between the shadowhunters that bound them to each other. How strong will their link be in the face of hardship and desperation?
1. Prologue

**BE MY PARABATAI**

**Note: This story was planned before CP and started before CP2 (yes i know, it's been a while...) so please forgive the outdated-ness.**

**After I finished reading Clockwork angel, I found the pair Jem/Will especially intriguing, (as if Cassie didn't hint it enough) and thought hard of some that would work. Something came to me and I said to myself, Why not? I'll give it a shot. This fic was originally planned to be up before CP came out, but ah well. CP broke my heart and I sometimes pray that Magnus will just kidnap Will and be done with it! (but otherwise enjoy~)**

**Disclaimer: Don't we all wish we owned the Infernal devices? Yes of course we are jealous Ms Clare.**

* * *

PROLOGUE

JAMES Carstairs walked into the institute, guided blindly by brother Enosh in the dim lit hallway. The moist stench filled Jem's nostrils and clung to his skin uncomfortably. The air here tastes different. There was only one occasion previously when he has been to The Institute in London, and that had only allowed for a short stay. He hadn't been granted the opportunity to closely observe the place properly, but the first thing he picked up was that it was gravely different to the institute in Shanghai.

The hallway was cold, and the entry walkway was excruciatingly narrow for such an enormous structure. He noticed on the way in, engraved on the arc were the words "Pulvis et umbra sumus", similar to the one in Shanghai, minus the Chinese translation. Jem frowned, instantaneously home sick. Although he'd spent his last few years in the silent city, the institute somehow brought back memories of his dead parents.

"_come"_ Brother Enosh's voice echoed in Jem's head, and he obeyed, sticking to the brother so closely he could feel the vibrations of his robe in the air before his face. They arrived at a room with towering bookshelves, where a lady in black sat at the single desk in the middle of the room. The flickering of the candle light projected tortured shadows across the room, making Jem's stomach knot.

"_I've brought him. We have decided that it was best he remained in England."_Brother Enosh informed the shadowhunter.

"Thank you Enosh." The woman said, dazed. Jem faintly remembered the woman from his previous visits.

"And this is James Carstairs?" She turned to face Jem. "I'm Charlotte Branwell, and I run the institute here."

Jem nodded slightly, definitely recalling his father talk about her.

"Yes. Mrs Branwell." Jem replied.

"Please call me Charlotte." Charlotte smiled again, and the knot in his stomach loosened.

After bidding a quick goodbye to brother Enosh, and a promise from him of returning soon, Charlotte led Jem through the unfamiliar hallways to a grand set of double doors. Upon entry, Jem quickly recognised it as the training room.

"Will, Thomas, we have a new visitor." Charlotte spoke to the two figures in stance, baring equally surprised expressions on their faces.

"This is James Carstairs." Charlotte finished, "and he is here to stay."

Jem stared as the couple placed the weapons on the floor, not accustomed to seeing _three _shadowhunters in one day when he'd been denied to see _anyone_ for months. It was strange that even though the dark haired boy was bare to the waist, Jem could not spot any evidence of markings. _Perhaps he had not received them yet?_He directed his attention to the other boy, who bore the most enthusiastic smile. He wiped his hands on his trousers and held it out.

"I'm Herondale, William Herondale." The boy introduced.

Jem took his hands and looked into his crisp blue eye, which seemed to welcome him without doubt.

"And this is Thomas." He pointed to the other boy, who smiled and inclined his head.

After the introduction, Charlotte had, unfortunately, more important matters to attend to, and left the touring of the institute with the two boys now standing before Jem. She made a quick apology before scurrying along the way they came, most likely back to the library.

"We're done for the day anyway." Will explained, and proceeded to packing the weapons and tools. Jem watched as the two shadowhunters worked. He paid close attention, especially to Will, who despite being covered in sweat and salt, looked tremendously handsome. Jem found it hard to gaze away, eyes tracing the swirling patterns of the marks on Will's torso.

William and Thomas led Jem through the assorted hallways and to the absurd rooms of the institute, including the unused storerooms and the series of strictly do-not-open doors. Jem couldn't help but stare as the back of William's hair lit up angelically every time they passed a torch. _Were_ _all shadowhunters in England this beautiful? _

It was later that evening that Jem was introduced to Jessamine – Jessie Lovelace, whom William paid little attention to, and Henry Branwell, the bubbly man to whom Charlotte was wed. To his reassurance, no one at the table had asked of his family or background. He was aware that the Silent brothers had informed Charlotte of his past prior his arrival, and was grateful she said nothing of it.

After desert, Jem was shown to his room, to which he would reluctantly retreat to without the company of others.

Will seemed to have picked up the frown on his face.

"You don't seem awfully pleased to see it. Is it the bed sheets? I can arrange that to be changed." Will offered.

"No, it's just… I'm homesick. This reminds me a lot of the institute in Shanghai." Jem spoke openly for the first time he arrived. "Thank you for the tour."

Will smirked. "It's all part of the job."

"William…" Jem called as he turned to go.

"Call me Will."

"Will, why was Thomas not at dinner? Is he…?" Jem asked.

"Thomas isn't a shadowhunter." Will said, disappointed. _That explains the absence of marks._

"He's a mundane who was granted the sight." Will continued. "He's a servant of the Nephilim."

Jem nodded, and bade Will goodnight, shutting the door regretfully, as he is fully aware that he will not be able to sleep. That evening, he lay awake holding the box of demon powder brother Enosh had given him, the only possession of his own in his new 'home'.

He turned and tossed on the bed, but sleep would not come. After several desperate tries of forcing his eyes shut, Jem gave up in exasperation and decided to explore the room.

Every room in the institute was almost identical, containing a bed, bed side drawers, a closet and some decorations chosen at random. Jem recognised some decorations in this room were imported from China; tea sets, cupboards and pieces of carvings and paintings. Perhaps someone has chosen this specific room to make Jem more at home, no doubt Charlotte or Jessamine might've done it, and he was grateful.

He opened each of the drawers, most of which are empty save a few dust balls and left over pieces of wood; nothing of interest. Next he approached the large wooden cupboard with a design carved with meticulous care by hand. He traced his hands over the patterns, admiring the impressive handiwork. Finally, unable to contain his curiosity, Jem wrapped his hands around the handle and pulled the doors open, to reveal a violin and bow mounted on a gleaming silver stand.

Jem carefully lifted the instrument from its resting position, handling it with caution. He placed it on top of the cupboard and ran his hands along, feeling the thickness of the strings. _Could he still handle it? It's been two years…_Jem shrugged the hesitation away and brought the instrument to his neck. After tuning with a bit of difficulty, Jem closed his eyes and focused on remembering a song. _Any song…_His fingers began to move, and the bow ran across the strings like it belonged…

"I didn't know you played." A voice interrupted the sweet flow of the music.

Jem stopped playing at the sound of Will's voice. He spun around to see the shadowhunter standing at the doorway, in his undergarments, rubbing his hair.

"I'm sorry… The music woke you up?" Jem apologised with a slight apologetic frown. "I couldn't sleep."

"You'll get used to it here." Will said with a smile, and showed a hint of sadness on his face. But the sadness disappeared quickly, and it was replaced by interest and curiosity.

"Well, since you can't sleep, I'll keep you company for a while." Will helped himself to the edge of the bed. Jem smiled at his guest.

Jem was about to resume playing when Will's hand crept towards the silver box on the bed side table. "what's-?" Will began.

"Don't, touch that." Jem shot, sounding a bit harsher than he meant to. Will withdrew his hand quickly and seemed astounded. Jem muttered an apology "Sorry, It's just…" And placed the violin back on the draw and took the box into his own hands.

"Sorry." Jem said again.

"What is it?" Will said, concerned at Jem's strange reaction.

"Its… I… It's demon powder." Jem explained quitely, after hesitation. There was silence. "I'm… not well."

Jem bowed his head in his hand, concealing the box in his cupped hand, waiting for Will to storm out, to call him a freak, to run away from the monster he is. But after none of those things happened, Jem released his breath and looked up. Will sat patiently on the side of his bed waiting for Jem to resume playing, clearly attempting to conceal his curiosity.

"I'm sorry." Jem apologised again. "It happened a long time ago…"

"You don't have to." Will cut him off suddenly. "I can't tell you anything in exchange."

Jem merely smiled and shook his head. "If I'm going to stay, then you should know the truth…"

That night was the beginning of a close relationship between the two boys.

Jem became more and more settled in the institute as time went past, able to fight for a few hours of sleep every night. Will found a new sparring partner who kept up with him, even though Thomas was fast, and strong among the mundane, he could not beat the heightened strength of the shadowhunters. And progressively it became universally obvious that the only person Will wasn't an ass to, is Jem.

Jem loved Will as a brother, and as a best friend. His room became a frequently visited place for Will's late evening strolls, to check if Jem had had enough of his _medicine._It soon became a ritual that Will came to check on him every night, and whenever Jem had _one of his days,_Will would tend to him, and make sure he was all right.

Jem swore, by the angel, that he would protect Will, and love him forever on end, for as long as he was alive.

And it was by that oath which Jem was screaming at, as Mortmain and his clockwork creatures dragged his parabatai away.

**A/N Didn't intend the chapter to be this long, but action starts next one so stay tuned! As nobody probably have noticed, I've taken a lengthy ff haitus, and have no idea if this is worth continuing. So feedback please?**


	2. Chapter 1

**So since this was partly planned and written before CP, I've fixed up some parts accordingly, but I've got no idea what to do with Jessie (since her betrayal was so unexpected), so just pretend the enclave released her back to the institute after some sort of reprimand I guess. And I just finished CP2 and I'm kind of heartbroken so my condolences go out to all of you and hope you enjoy.**

"Do what you like, William. You always do." _Jem Carstairs_

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One

Fire messages arrived at the institute like confetti at a celebration, illuminating the usually dim library and everyone inside it. Small pieces of torn paper drifted into the open with more or less "clockwork creatures" scrawled quickly across them; no doubt their construction had been in haste. Confusion set in as 8 pairs of eyes focused on Charlotte, whose look was unmistakable, they were under attack.

All but Tessa were geared, including Sophie and Cyril, despite her plausible argument and pleas to help. The enclave's final decision was very clear: Tessa was going to stay, and to be protected at all cost.

Alongside the celebrations that flew past in the few months of low demonic and clockwork activity, the residents of the London institute have been preparing themselves for a bloody battle, devising plans to overcome the Mortmain's army. And the planning had not been easy, for who could prepare for something they had so little knowledge of? Worst of all, their efforts did not for a second mean mortmain did not have plans of his own, now in possession of the Pyxis; after all Mortmain was not known to give up so easily.

Henry, making slow progress in his work shop, is trying to design a device which will altogether shut these creatures down, but it is a progress with little success. No one knew what these creatures were prone to, or how to kill them other than decapitation or utter destruction. The only device which proved to have _any_ effect on the monsters was destroyed by Henry after the accidentin the warehouse who, despite everyone's protests, forbade further use of a machine that risked anybody's life.

Soon the preparatory tasks came to a conclusion, and the shadowhunters reunited in the main lounge, which overlooked the front and rear of the institute through huge enchanted glass windows, which are made to look like brick walls from the outside. The group stared silently out the window in unison, waiting and anticipating for the worst.

Jem sat in an armchair with Charlotte on a stool to his right and Henry and Gideon beside her. Jessie sat with her face in her hands with Sophie and Cyril on either side of her, having agreed to help out of thanks for Charlotte's hospitality and kindness. Behind Jem stood Will, who gripped the armchair with such force that his knuckles have paled.

"I still think I should be the main assault." Will said, breaking the silence, his voice tainted with a hint of impatience. "Why can't Jem be our backup, I can assure you that he will perform the duty better than I-"

"Will, we have discussed this matter previously, and I am not taking anymore suggestions. You will serve as the institute's last line of defence, in case…" Charlotte sighed, sparing a glance out the window while she repeated the same thing for what seems like the one thousandths time.

"So is the institute more important than the lives of our comrades in this war? It's almost going to guarantee a defeat. Let me fight at the front." Will pursued.

"Do you doubt our ability to fight William Herondale?" It was Jem that spoke this time in his usual calm demeanour, as Charlotte shook her head hopelessly.

"Of course not, but that's beside the point- You know what I mean James!" Will said as he ran his hand through his ruffled hair, a frown already forming on his forehead.

"Will, I didn't see you being so doubtful when you were fighting my brother." Gideon defended, "now that you have an addition to your party, where do your worries lie?"

"I didn't-" Will didn't doubt the Lightwood's ability to fight; Gideon has proven to be a valuable addition to the family, instructing Sophie and Tessa with the patience Will has never dreamt of possessing, and Will was confident that he would protect Jem with his life also, except-

"It is also crucial for the protection of Tessa. We are not fighting this war for our own sakes Will, it is to stop Mortmain from succeeding, and you know better than anyone else what it takes to do that." Jem added in a soothing voice.

Will pulled a face and brought his mouth closer to Jem's ear and whispered with a sigh. "You know I'm worried about you, don't you?"

"Yes, I do William, and I'll be fine." Jem replied in a similar voice.

It was clear that Jem did not want to discuss the matter any further, and Will did not press on it. He did occasionally tried the patience of his saintly parabatai, but he knew his bounds, and most important of all respected Jem's wishes. Instead he joined the others in staring out the window onto the grey looking front yard, anticipating any tiny speck of movement.

The gate creaked and the shadowhunters tensed. Someone was coming - the clockworks were here. Jem stood up at the same time Jessie did, picking up his cane as Jessie wielded her umbrella. The room began to stir as an unspoken prayer went out to each member of the group, for no one could guarantee that they would see each other again. Will however, did not move. He stared at the gate intensely, as if his gaze could make the gate shut again.

"Is everyone ready?" Jem called, geared fully with chakrams, seraph blades and his stele. "Will?"

No reply came from Will, and the room fell silent as the group paused and followed his fixed gaze at the gate outside. Visible was a fleshed hand instead of mechanics. What appeared wasn't a clockwork creature, but a mundane.

The shadowhunters stared, momentarily frozen with shock at the appearance of a mundane on institute grounds. Such rare sight was not rewarded often; in fact Charlotte was hardly sure that there has ever been a recorded case of such foolishness. It almost seemed like the angels were playing some sort of cruel joke on their human descendents. The group stood very still, unsure what to do.

"What are we going to do?" Henry echoed everyone's thoughts after a minute or so, unable to keep the surprise out of his voice. "He's going to get killed!"

"Surely we can invite him in for a cup of warm tea, and maybe offer some biscuits for the road on his way out." Will said bitterly.

"Really? At a time like this Henry? You worry about the man's life? He could as well ruin our whole plan! Mortmain's clockworks are due any moment!" Charlotte replied with restrained frustration in her voice as she shot Will her deadliest glare.

"Charlotte, we're not sure if this isn't a decoy. Mortmain isn't stupid." Jem said carefully.

"He could have easily sent one of his friends to-." Jessie said, with anxiety in her voice.

"Well, then he obviously didn't see the sign on the front door." Will retorted, his voice dripping with sarcasm.

"Never mind that, he has to go." Charlotte waved away the speculations. "He's a mundane after all. The clockworks wouldn't be so accurate in depicting humans yet."

"Well, an easy glamour should do it." Jem said, I can-"

"I'll go." Will offered without pause.

"No, Will you'll stay." Charlotte shot.

"No, _I'll _go." Jessie spoke. Six heads turned towards her. "Oh, I can't do much fighting anyway, and this I can. I'll drive him away and come right back." She turned on her heels and strode out.

Jem didn't miss a step as he spun around and exited the room after the lady. Will made to follow but was a second too late as Charlotte caught at his sleeve. "They need someone to keep watch!"

"Jem can keep watch." Charlotte reassured. "They'll be back soon." _Hopefully in one peace. _

Will opened his mouth as if he was going to say more, but no sound came out. Unwillingly, he planted himself in the seat nearest to the door and buried his face in his hands, sighing loudly.

Jem quickened his step until he caught up to the blonde haired girl and was striding beside her. It did not escape him that she was nervous, her shoulders were stiff and she moved with great haste as if she was in a hurry. Before Jem could point the fact out to his companion, Jessie gave a little gasp as she reached the stairs at the end of the hallway, and absentmindedly missed the top step. Before she could let out a full scream, she found herself in Jem's soft embrace, from when Jem dropped his sword-cane and dashed forward to catch her in his arms.

After righting herself, with the gentleman's help, she brushed her gear free of wrinkles and blushed without meaning to.

"You ought to be more careful Miss Lovelace," Jem spoke gently as he retrieved his cane from where it had fallen. "It is not every day that you will find yourself in a man's arms when you do decide to tumble down the stairs again."

Usually Jessie would have turned her head and stalked off from such a rude comment, but this time, she could not help but smile at the boy standing before her as she realised that he was trying to relieve her of her worries. "Thank you, Mr Carstairs." She returned kindly. "I shall be more careful in the future."

Jem nodded his acknowledgement and continued to descend the spiral stair case with Jessie closely at his heels. "You know, sometimes you are more like Will than one can tell from first sight." Jessie said as they reached the second floor.

Jem raised an eyebrow at the observation. "Oh?"

"I am not blind to his attraction to you." Jessie continued. "The way he offered himself in the lounge, that was very noble of him."

"And it is also very noble of a young lady like you to rush into danger by herself." Jem replied and offered a small smile.

Jessie said nothing; she could not help but feel a wave of sadness overcome her as she thought _I have been fighting all my life against my fate, against the blood that ran through my veins_. As they reached the lobby leading to the front door, Jem paused as he took out a stele to mark himself with a voyance rune. Jessie took one last look at her fellow shadowhunter and tightened her grip around her umbrella.

"Are you ready?" Jem asked as he rolled his sleeve back down.

Jessie nodded in response. As she pushed open the great oak doors of the institute open, filled with renewed hope and confidence, she thought _maybe the shadowhunters weren't so bad after all._

Two figures stepped out onto the vast entrance of the institute, easily recognisable as Jem and Jessie. They walked gracefully together towards the mundane, who turned as he noticed them. Jem was obviously glamoured as the man only addressed Jessie, and from the institute window, everybody watched in silence as they exchanged greetings. After what seemed like an eternity, the man turned around and headed back the way he came, and Will's heart leaped as relief washed over him. _Everything is well, Jem and Jessie are safe._

The mundane headed back to the gate, leaving, but instead of returning to the safety of the institute, Jem and Jessie followed.

"What?" Will exclaimed loudly, unaware that he had spoken "are they doing?"

"I don't know!" Charlotte replied in a voice that surpassed Will's shock.

Will stood up and took a step towards the exit, only to be restrained by Charlotte again.

"You can't just walk out!" Charlotte spoke with desperation.

Will frowned and turned around, "Tell that to Jem and Jessie!" He hissed back, in the same tone.

"We will wait for them to come back. They're able." Gideon said, dragging a very angry Will back to his seat.

Will's heart hammered against his sternum while he flipped the Herondale dagger that once belonged to his father over in his hands. Every positive thought met uncertainty, and every moment he could not see Jem sent shivers down his spine. _What if something happens to him? _Will cringed at the thought of Jem being hurt. _Then I will be the world's worst parabatai. _He cursed.

Tension grew as the four shadowhunters and their companions sat in the hollow lounge, praying to the angels in silence.

The landscape soon grew tiresome and the change in it was so sudden that Will jumped out of his chair with inhuman speed as two familiar figures finally appeared and grew larger. Jem and Jessie were sprinting at their limits back towards the institute; followed by a crowd of clockwork creatures.

Will didn't waste a second. He grabbed his blade and dashed to the stairs down the hallway, his heart beating loud in his ears. Behind him he could hear the muffled footsteps and voice of Charlotte calling his name.

"Will"

He didn't slow down, his mind focused on Jem and Jessie. _Jem..._

"William." he heard his name again.

He jumped down the stairs two at a time, the exit was near.

On the last turn to the front door a hand jerked him back with extraordinary force.

"William Herondale." Charlotte scowled.

"Let me go." will begged, eyes daring her to let go.

"No, we have to get to station." she said as Henry and Gideon charged towards the front door with Cyril at his heels.

"But Jem-"

Charlotte grabbed him and pushed will back into the stairs. "We have to go. We can help at the tower."

With charlotte pushing behind him, Will took one more glance towards the door and obeyed.

The sight from the highest point of the institute was usually calming, except now it bore blood and battle. The view made will's stomach churn uncomfortably. He spotted Jem almost immediately, in the middle of the chaos slashing at the monsters with silver flashes of his cane. They were so hopelessly outnumbered.

Will held up his bow and nocked an arrow, pulling back the tight string with ease, and fired. The creature sneaking up to Jessie jerked backwards and shook violently before it dropped to the ground as the arrow lodged itself in the side of its neck.

The front yard seemed so small with hundreds of clockwork creatures. Will looked helplessly at the scene; _he was running out of arrows_. Guilt overwhelming inside, he was supposed to be there. To watch Jem's back, to fight as one with his brother in arms. His heart ached and a shiver ran down his whole body like millions of tiny drops of water needles piercing his skin. _Where were the backup the enclave had offered? _Will thought with frustration and made a mental note to personally strangle Gabriel and his demon lover of a father next time they crossed paths.

Time passed as the shadowhunters retreated and were worn and battered by the creatures, but the stream of clockworks never ceased. The yard was dyed with blood and surfaced with metal pieces; body parts, cogs, screws-. He stared at the bloody encounter before him, with blood boiling through his veins. _Wake me up._ He thought. _Wake me up from this hideous nightmare._

"Will." A distant voice called him back to solid ground. "William…" the voice beckoned. "It is time."

The deafening noise of the fighting has ceased and Will sucked in a cold breath as he observed the condition of the battlefield. They had been defeated. The creatures have retreated and he could see Mortmain. _Mortmain. _

**Flames and Flowers are welcome :)**


End file.
